WO2009116329A1 - Steering operation device - Google Patents

Abstract

A steering operation device satisfactory operable irrespective of the shape of the vehicle body. In the steering operation device, cylinders (2, 3) are driven by hydraulic pressure and change the steering angle of the vehicle. A steering valve (42) adjusts, according to a pilot pressure, the flow rate of oil supplied to the cylinders (2, 3). According to a difference between the rotational angle of an operation input shaft (54) and the rotational angle of a feedback input shaft (55), a pilot valve (52) adjusts a pilot pressure inputted into the steering valve (42). A joystick lever (5) is connected to the operation input shaft (54) and rotates the operation input shaft (54) according to a tilt angle. A drive device (6) rotates the feedback input shaft (55). A steering angle detecting section (7) detects a steering angle and output the result as a detected signal. A control section (8) sends a command signal to the drive device (6) so that the drive device rotates the feedback input shaft (55) according to the detected steering angle.

Description

Steering device

The present invention relates to a steering operation device.

A so-called joystick lever type is known as a steering operation device for controlling the steering angle of a vehicle. In this joystick lever type steering operation device, the operator can change the steering angle of the vehicle by tilting the joystick lever provided in the driver's seat.

For example, the steering operation device disclosed in Patent Document 1 includes a pair of hydraulic cylinders, a steering valve, and a pilot valve.

The hydraulic cylinder is provided across the front vehicle body and the rear vehicle body. When these hydraulic cylinders expand and contract, the angle between the front vehicle body and the rear vehicle body, that is, the steering angle is changed.

The steering valve adjusts the flow rate of oil supplied to the hydraulic cylinder according to the input pilot pressure.

The pilot valve has an operation input shaft and a feedback input shaft that are relatively rotatable. The operation input shaft is connected to the joystick lever and rotates according to the tilt angle of the joystick lever. The feedback input shaft is connected to the front vehicle body by a link member. When the change in the steering angle is transmitted to the feedback input shaft by the link member, the feedback input shaft rotates. Thereby, the feedback input shaft rotates in accordance with the steering angle. The pilot valve adjusts the pilot pressure input to the steering valve in accordance with the difference between the rotation angle of the operation input shaft and the rotation angle of the feedback input shaft. Further, when the joystick lever is operated, the steering operation device operates as follows.

First, when the joystick lever is tilted to one side, the pilot valve operation input shaft rotates according to the tilt angle. At this time, the steering angle has not been changed, and the rotation angle of the feedback input shaft is zero. For this reason, the pilot valve is opened at an opening degree corresponding to the rotation angle of the operation input shaft, and the pilot pressure is supplied to the steering valve. The steering valve supplies oil of a flow rate corresponding to the input pilot pressure to the hydraulic cylinder. As a result, the hydraulic cylinder is driven and the steering angle is changed.

When the steering angle is changed following the tilt operation of the joystick lever as described above, the link member is moved by the change of the steering angle, and the movement of the link member is transmitted to the feedback input shaft. Here, when the steering angle matches the tilt angle of the joystick lever, the difference between the rotation angle of the operation input shaft and the rotation angle of the feedback input shaft becomes zero. As a result, the pilot valve is closed and the steering valve is also closed. For this reason, the change of the steering angle is stopped, and the steering angle is fixed in a state where it matches the tilt angle of the joystick lever.

Thus, in the above steering operation device, a steering angle corresponding to the tilt angle of the joystick lever can be obtained, and the operability can be improved.
JP-A-11-105723

However, in the steering operation device as described above, since the pilot valve is connected to the joystick lever by the link member, it is necessary to arrange the pilot valve at a location close to the joystick lever. For this reason, depending on the shape of the vehicle body, the distance from the pilot valve to the front vehicle body increases, and an excessively long link member is required. In this case, it becomes difficult to provide the link member.

An object of the present invention is to provide a steering operation device with good operability regardless of the shape of the vehicle body.

The steering operation device according to the first invention includes a hydraulic actuator, a steering valve, a pilot valve, a joystick lever, a drive device, a steering angle detection unit, and a control unit. The hydraulic actuator is driven by hydraulic pressure to change the steering angle of the vehicle. The steering valve adjusts the flow rate of oil supplied to the hydraulic actuator in accordance with the input pilot pressure. The pilot valve has a movable operation input member and a feedback input member, and adjusts the pilot pressure input to the steering valve according to the difference between the displacement amount of the operation input member and the displacement amount of the feedback input member. To do. The joystick lever is provided so as to be tiltable when operated by an operator, and is connected to the operation input member, and displaces the operation input member in accordance with the tilt angle. The drive device displaces the feedback input member according to the input command signal. The steering angle detector detects the steering angle and outputs it as a detection signal. A detection signal from the steering angle detection unit is input to the control unit. And a control part sends a command signal to a drive device so that a feedback input member may be displaced according to an inputted steering angle.

In this steering operation device, the change in the steering angle is input to the control unit as a detection signal from the steering angle detection unit. And a control part can displace a feedback input member so that it may become the amount of displacement according to a steering angle by sending a command signal to a drive device. Therefore, feedback of the steering angle is possible without providing a link member. For this reason, in this steering operation device, operability can be improved regardless of the shape of the vehicle body.

In this steering operation device, the drive device is electrically controlled. However, since the joystick lever and the operation input member are connected, the pilot valve is non-electrically controlled by operating the joystick lever. Can do. For this reason, even if a trouble occurs in the electric system, feedback of the steering angle is impossible, but it is possible to change the steering angle. For this reason, it is possible to avoid a dangerous situation in which the vehicle body cannot be bent at all, and to improve safety.

The external perspective view of a motor grader. The hydraulic circuit diagram which shows the structure of a steering operating device.

Explanation of symbols

1 Steering operation device 2, 3 Steering hydraulic cylinder (hydraulic actuator)
5 Joystick lever 6 Driving device 7 Steering angle detector 8 Controller 42 Steering valve 52 Pilot valve 54 Operation input shaft (operation input member)
55 Feedback input shaft (feedback input member)

1. Configuration 1-1. Overall Configuration FIG. 1 shows a motor grader 100 provided with a steering operation device 1 according to an embodiment of the present invention. FIG. 1 is an external perspective view of the motor grader 100. The motor grader 100 includes six traveling wheels including a pair of left and right front wheels 11 and two rear wheels 12 on each side. The motor grader 100 can perform leveling work and snow removal work with a blade 19 provided between the front wheel 11 and the rear wheel 12. In FIG. 1, only the one located on the left side of the four rear wheels 12 is illustrated. The motor grader 100 includes a frame 13, a driver's cab 14, and a work machine 15.

The frame 13 includes a rear frame 16 and a front frame 17 as shown in FIG.

The rear frame 16 houses an engine (not shown), hydraulic pressure sources 41 and 53 (see FIG. 2), and the like. Further, the rear frame 16 is provided with the four rear wheels 12 described above, and the vehicle can travel when the rear wheels 12 are rotationally driven by the driving force from the engine.

The front frame 17 is attached to the front of the rear frame 16 and has a long shape in the front-rear direction. A front wheel 11 is attached to a front end portion of the front frame 17 via a front wheel support frame 18.

The cab 14 is placed on the rear frame 16. Various operation members such as a handle and a shift lever are disposed inside the cab 14. A joystick lever 5 described later is also disposed in the cab 14.

The work machine 15 includes a blade 19, a hydraulic motor (not shown), and various hydraulic cylinders 21 to 23. The blade 19 is attached to the front frame 17 via a draw bar 24 and a circle 25. The work implement 15 can perform a lift operation for moving the blade 19 up and down and a tilt operation for changing the inclination of the blade 19 by driving the hydraulic motor and the hydraulic cylinders 21 to 23.

1-2. Next, a configuration of the steering operation device 1 provided in the motor grader 100 will be described with reference to FIG. The steering operation device 1 includes a pair of steering hydraulic cylinders 2, 3, a steering hydraulic circuit 4, a joystick lever 5, a driving device 6, a steering angle detection unit 7, and a control unit 8.

The pair of steering hydraulic cylinders 2 and 3 are driven by hydraulic pressure. The steering hydraulic cylinders 2 and 3 are attached to the rotating portions 18 a and 18 b of the front wheel support frame 18 and change the angle of the pair of front wheels 11. The rotating portions 18 a and 18 b are members to which the front wheels 11 are attached, and are provided on the left and right sides of the front wheel support frame 18 so as to be rotatable. These rotating portions 18a and 18b are connected to each other by a tie rod 29, and the angle is changed integrally. As a result, the angle of the front wheel 11 relative to the longitudinal direction of the vehicle body of the motor grader 10, that is, the steering angle θs is changed.

In the following description, the left steering hydraulic cylinder 2 is referred to as a “left cylinder 2”, and the right steering hydraulic cylinder 3 is referred to as a right cylinder 3.

Each of the hydraulic cylinders 2 and 3 for steering is provided with expansion ports 21 and 31 and contraction ports 22 and 32, respectively. When oil is supplied to the expansion port 21 of the left cylinder 2 and the contraction port 32 of the right cylinder 3 and oil is discharged from the contraction port 22 of the left cylinder 2 and the expansion port 31 of the right cylinder 3, the left cylinder 2 It extends and the right cylinder 3 contracts. As a result, the steering angle θs changes and the vehicle turns to the right. When oil is supplied to the contraction port 22 of the left cylinder 2 and the expansion port 31 of the right cylinder 3, and when oil is discharged from the expansion port 21 of the left cylinder 2 and the contraction port 32 of the right cylinder 3, the left cylinder 2 contracts and the right cylinder 3 extends. As a result, the steering angle θs changes in the direction opposite to that when turning right, and the vehicle turns to the left.

The steering hydraulic circuit 4 is a circuit for adjusting the flow rate of oil supplied to the steering hydraulic cylinders 2 and 3. The steering hydraulic circuit 4 has a main hydraulic circuit 40 and a pilot hydraulic circuit 50.

The main hydraulic circuit 40 is a circuit for supplying oil from the main hydraulic source 41 to the steering hydraulic cylinders 2 and 3, and a steering valve 42 is provided. Note that the main hydraulic power source 41 includes, for example, a hydraulic pump, a relief valve, and the like.

The steering valve 42 is a flow rate control valve that adjusts the flow rate of the oil supplied to the steering hydraulic cylinders 2 and 3 according to the input pilot pressure. The steering valve 42 has a main pump port P1, a main drain port P2, a first steering port P3, and a second steering port P4. The main pump port P1 is connected to the main hydraulic power source 41. The main drain port P2 is connected to a tank T that collects oil. The first steering port P3 is connected to the contraction port 22 of the left cylinder 2 and the expansion port 31 of the right cylinder 3. The second steering port P4 is connected to the extension port 21 of the left cylinder 2 and the contraction port 32 of the right cylinder 3.

Further, the steering valve 42 has a valve body 43 that can move to a neutral position Ns, a left steering position Ls, and a right steering position Rs. When the valve body 43 is in the neutral position Ns, the main pump port P1 and the main drain port P2 communicate with each other. Further, the first steering port P3 and the second steering port P4 are not connected to any port. When the valve body 43 is in the left steering position Ls, the main pump port P1 and the first steering port P3 communicate with each other, and the main drain port P2 and the second steering port P4 communicate with each other. When the valve body 43 is in the right steering position Rs, the main pump port P1 and the second steering port P4 communicate with each other, and the main drain port P2 and the first steering port P3 communicate with each other.

Further, the steering valve 42 has a first pilot chamber 44 and a second pilot chamber 45. When the pilot pressure is not supplied to the first pilot chamber 44 and the second pilot chamber 45 and when the same pilot pressure is supplied to the first pilot chamber 44 and the second pilot chamber 45, the valve body 43 is Located at neutral position Ns. In a state where the pilot pressure is supplied only to the first pilot chamber 44, the valve body 43 is located at the left steering position Ls. In a state where oil is supplied to the second pilot chamber 45, the valve body 43 is positioned at the right steering position Rs. When the valve body 43 is located at the left steering position Ls or the right steering position Rs, the steering valve 42 changes the opening area through which oil from the main hydraulic power source 41 passes according to the supplied pilot pressure. . Thereby, the steering valve 42 adjusts the flow rate of the oil supplied to the right cylinder 3 or the left cylinder 2 according to the pilot pressure.

The pilot hydraulic circuit 50 is a circuit for supplying oil from the pilot hydraulic source 53 to the first pilot chamber 44 and the second pilot chamber 45 of the steering valve 42. The pilot hydraulic circuit 50 is provided with a variable pressure reducing valve 51 and a pilot valve 52. The pilot hydraulic power source 53 can supply oil having a pressure higher than the maximum output hydraulic pressure of the variable pressure reducing valve 51, and includes, for example, a pilot hydraulic pump or a relief valve.

The variable pressure reducing valve 51 reduces and adjusts the hydraulic pressure sent from the pilot hydraulic source 53 to the pilot valve 52. Further, the variable pressure reducing valve 51 can compensate for the minimum hydraulic pressure sent to the pilot valve 52. The variable pressure reducing valve 51 is an electromagnetic pressure reducing valve, and controls the hydraulic pressure in response to a command signal from the control unit 8.

The pilot valve 52 is a valve that adjusts the pilot pressure input from the pilot hydraulic power source 53 to the steering valve 42. The pilot valve 52 has a pilot pump port P5, a pilot drain port P6, a first pilot port P7, and a second pilot port P8. The pilot pump port P5 is connected to a pilot hydraulic power source 53 via a variable pressure reducing valve 51. The pilot drain port P6 is connected to a tank T that collects oil. The first pilot port P7 is connected to the first pilot chamber 44 of the steering valve 42. The second pilot port P8 is connected to the second pilot chamber 45 of the steering valve 42.

The pilot valve 52 has a valve body 56 that can move to a neutral position Np, a left pilot position Lp, and a right pilot position Rp. When the valve body 56 is in the neutral position Np, the pilot pump port P5, the pilot drain port P6, the first pilot port P7, and the second pilot port P8 communicate with each other. When the valve body 56 is in the left pilot position Lp, the pilot pump port P5 and the first pilot port P7 communicate with each other, and the pilot drain port P6 and the second pilot port P8 communicate with each other. When the valve body 56 is in the right pilot position Rp, the pilot pump port P5 and the second pilot port P8 communicate with each other, and the pilot drain port P6 and the first pilot port P7 communicate with each other.

The pilot valve 52 has an operation input shaft 54 and a feedback input shaft 55. The operation input shaft 54 is rotatably provided around the central axis. The feedback input shaft 55 is disposed coaxially with the operation input shaft 54 and is disposed so as to be rotatable around the central axis. In the pilot valve 52, the valve body 56 moves according to the difference Δθ between the rotation angle θin of the operation input shaft 54 and the rotation angle θfb of the feedback input shaft 55, and the neutral position Np, the left pilot position Lp, the right pilot Move to position Rp. When the rotation angle difference Δθ is zero, the valve body 56 is positioned at the neutral position Np. When the valve body 56 is located at the left pilot position Lp or the right pilot position Rp, the pilot valve 52 changes the opening area through which oil from the pilot hydraulic power source 53 passes according to the difference Δθ in rotation angle. . Thereby, the pilot pressure sent from the pilot valve 52 to the steering valve 42 is adjusted in accordance with the rotation angle difference Δθ. The pilot valve 52 is provided in the rear frame 16 and is disposed in the vicinity of the joystick lever 5. Further, the operation input shaft 54 is provided with a first rotation angle detector 61, which detects the rotation angle θin of the operation input shaft 54. The feedback input shaft 55 is provided with a second rotation angle detection unit 62 and detects the rotation angle θfb of the feedback input shaft 55. The rotation angles θin and θfb detected by the first rotation angle detection unit 61 and the second rotation angle detection unit 62 are sent to the control unit 8 as detection signals.

The joystick lever 5 is provided in the cab 14 and is a member operated by an operator. The joystick lever 5 is provided so as to be tiltable left and right. The joystick lever 5 is connected to the operation input shaft 54, and the operation input shaft 54 is configured to be rotationally displaced according to the tilt angle of the joystick lever 5. Specifically, the operation input shaft 54 rotates by the same angle as the tilt angle of the joystick lever 5. The joystick lever 5 is not limited to being directly coupled to the operation input shaft 54, but may be coupled via a mechanical coupling structure such as a gear or a link member.

The driving device 6 is a device driven by electric power, and rotationally displaces the feedback input shaft 55 in accordance with an input command signal. The drive device 6 includes, for example, a servo motor, and the rotation shaft of the servo motor is connected to the feedback input shaft 55. The drive device 6 and the feedback input shaft 55 are not limited to being directly coupled, but may be coupled via a mechanical coupling structure such as a gear or a link member. The driving device 6 is disposed in the vicinity of the pilot valve 52.

The steering angle detection unit 7 detects the steering angle θs described above, and outputs the detected steering angle θs to the control unit 8 as a detection signal. The steering angle detector 7 is disposed in the vicinity of the front wheel 11 and is configured by, for example, a potentiometer.

The control unit 8 is configured by an arithmetic device such as a CPU and a storage device such as a RAM and a ROM, and outputs a command signal to the drive device 6 and the variable pressure reducing valve 51 by wire or wirelessly. Thereby, the control unit 8 can control the driving device 6 and the variable pressure reducing valve 51.

The steering angle θs detected by the steering angle detection unit 7 is input to the control unit 8 as a detection signal. The control unit 8 sends a command signal to the drive device 6 so as to displace the feedback input shaft 55 according to the steering angle θs. Specifically, the drive device 6 is controlled so that the feedback input shaft 55 rotates by the same angle as the steering angle θs. Thus, the steering angle θs is fed back to the pilot valve 52, and the steering angle θs can be changed according to the tilt angle of the joystick lever 5.

The control unit 8 receives the rotation angle θin of the operation input shaft 54 detected by the first rotation angle detection unit 61 and the rotation angle θfb of the feedback input shaft 55 detected by the second rotation angle detection unit 62 as detection signals. . Further, the vehicle speed V detected by the vehicle speed sensor 63 shown in FIG. 2 is also input to the control unit 8 as a detection signal. The control unit 8 controls the variable pressure reducing valve 51 based on the vehicle speed V, the rotation angle θin, and the rotation angle θfb. Thereby, the original pressure of the pilot pressure sent to the pilot valve 52 can be controlled so that the flow rate Q of the oil to the left and right cylinders 2 and 3 does not change abruptly.

2. Operation at the time of steering The operation at the time of steering will be described below.

When the joystick lever 5 is in the center position, the operation input shaft 54 is located at a predetermined initial position, and the rotation angle θin of the operation input shaft 54 is zero. The steering angle θs is also zero. For this reason, the feedback input shaft 55 is located at a predetermined initial position, and the rotation angle θfb of the feedback input shaft 55 is also zero. At this time, the valve body 56 of the pilot valve 52 is located at the neutral position Np. In this case, the pilot pressures of the first pilot chamber 44 and the second pilot chamber 45 of the steering valve 42 are the same, and the valve body 43 of the steering valve 42 is also located at the neutral position Ns. Accordingly, no oil is supplied to or discharged from the left and right cylinders 2 and 3, and the steering angle θs is maintained at zero. Then, a detection signal indicating that the steering angle θs is zero is sent from the steering angle detection unit 7 to the control unit 8. Since the steering angle θs is zero, the control unit 8 controls the driving device 6 so that the rotation angle θfb of the feedback input shaft 55 is maintained at zero.

Next, when the operator tilts the joystick lever 5 to the left from the center position, the operation input shaft 54 rotates in the same manner, and the rotation angle θin of the operation input shaft 54 increases. At this time, the steering angle θs is still zero due to a delay in the reaction of the left and right cylinders 2 and 3. Therefore, the rotation angle difference Δθ increases. Then, the valve body 56 of the pilot valve 52 moves to the left pilot position Lp, and the pilot pressure is supplied to the first pilot port P7. As a result, the valve body 43 of the steering valve 42 moves to the left steering position Ls. As a result, oil is supplied to the contraction port 22 of the left cylinder 2 and the expansion port 31 of the right cylinder 3, and the oil is discharged from the expansion port 21 of the left cylinder 2 and the contraction port 32 of the right cylinder 3. As a result, the steering angle θs gradually increases from zero. As a result, the front wheel 11 is directed leftward. This change in the steering angle θs is detected by the steering angle detector 7 and sent to the controller 8. The control unit 8 controls the driving device 6 so that the rotation angle θfb of the feedback input shaft 55 is the same as the steering angle θs.

When the operator stops the joystick lever 5 at a predetermined tilt angle θ1, the operation input shaft 54 also stops at the rotational angle θ1. On the other hand, since the steering angle θs gradually increases, the rotation angle difference Δθ gradually decreases. When the steering angle θs catches up with the rotation angle θ1, the rotation angle difference Δθ becomes zero. At this time, the valve body 56 of the pilot valve 52 is located at the neutral position Np, and the pilot pressure supplied to the first pilot chamber 44 and the second pilot chamber 45 of the steering valve 42 is the same. For this reason, the valve body 43 of the steering valve 42 is also located at the neutral position Ns. As a result, oil is not supplied to or discharged from the left and right cylinders 2 and 3, and the steering angle θs is maintained at the angle θ1. Thus, when the joystick lever 5 is stopped at the position of the predetermined tilt angle θ1 to the left, the steering angle θs is also maintained at the same angle θ1. Thereby, the front wheel 11 is maintained in the direction of the angle θ1 to the left.

Next, when the operator returns the joystick lever 5 to the center position, the operation input shaft 54 rotates in the same manner, and the rotation angle θin of the operation input shaft 54 decreases. At this time, the steering angle θs is still the angle θ1 due to a delay in the reaction of the left and right cylinders 2 and 3. Accordingly, the rotation angle difference Δθ decreases from zero and becomes negative. Then, the valve body 56 of the pilot valve 52 moves to the right pilot position Rp, and the pilot pressure is supplied to the second pilot port P8. As a result, the valve element 43 of the steering valve 42 moves to the right steering position Rs. As a result, oil is supplied to the expansion port 21 of the left cylinder 2 and the contraction port 32 of the right cylinder 3, and the oil is discharged from the contraction port 22 of the left cylinder 2 and the expansion port 31 of the right cylinder 3. As a result, the steering angle θs gradually decreases from the angle θ1. This change in the steering angle θs is detected by the steering angle detector 7 and sent to the controller 8. The control unit 8 controls the driving device 6 so that the rotation angle θfb of the feedback input shaft 55 is the same as the steering angle θs.

When the operator stops the joystick lever 5 at the center position, the operation input shaft 54 also stops at the initial position, that is, the position where the rotation angle θin is zero. On the other hand, since the steering angle θs gradually decreases from the angle θ1, the difference Δθ in the rotation angle gradually decreases. When the steering angle detection unit 7 detects that the steering angle θs has become zero, the control unit 8 drives the drive device so that the rotation angle θfb of the feedback input shaft 55 becomes zero, similar to the steering angle θs. 6 is controlled. Thereby, the difference Δθ in the rotation angle becomes zero. At this time, the valve body 56 of the pilot valve 52 is located at the neutral position Np, and the valve body 43 of the steering valve 42 is also located at the neutral position Ns. As a result, oil is not supplied to or discharged from the left and right cylinders 2 and 3, and the steering angle θs is maintained at zero. As described above, when the joystick lever 5 is returned from the predetermined tilt angle θ1 to the center position and stopped, the steering angle θs is also returned to zero and maintained. Thereby, the front wheel 11 is returned to the direction along the front-back direction.

The operation when the operator tilts the joystick lever 5 from the center position to the right side is also the same as described above, and the description is omitted.

3. Features With this steering operation device 1, feedback of the steering angle θs to the pilot valve 52 is possible without providing a link member. For this reason, in this steering operation device 1, operability can be improved even in a vehicle having a long distance from the front wheels 11 to the cab 14 as in the motor grader 100 described above.

In this steering operation device 1, the drive device 6 is electrically controlled. However, since the joystick lever 5 and the operation input shaft 54 are mechanically connected, the pilot valve can be operated by operating the joystick lever 5. 52 can be non-electrically controlled. For this reason, even if a trouble occurs in the electric system, the steering angle θs can be changed. For this reason, it is possible to avoid a dangerous situation in which the vehicle body cannot be bent at all, and to improve safety.

4). Other Embodiments In the above embodiment, the steering operation device 1 according to the present invention is provided in the motor grader 100. However, if the vehicle has a long distance between the mechanism that generates the steering angle θs and the pilot valve 52, the present embodiment is used. The invention is effective. For example, the steering device 1 according to the present invention may be provided in the wheel loader.

In the above embodiment, the left and right cylinders 2 and 3 are used as the hydraulic actuator for changing the steering angle θs, but the present invention is not limited to this, and other hydraulic actuators may be used.

In the above embodiment, the pilot valve 52 adjusts the pilot pressure by the rotational difference between the operation input shaft 54 and the feedback input shaft 55, but the pilot pressure is adjusted by the displacement difference due to other movements instead of the rotation. Also good.

In the above embodiment, the tilt angle of the joystick lever 5 and the steering angle θs are controlled to be the same. However, the tilt angle of the joystick lever 5 and the steering angle θs are not limited to being exactly the same. The tilt angle of the joystick lever 5 and the steering angle θs may be increased or decreased in a specific relationship.

In the above-described embodiment, a potentiometer is illustrated as the steering angle detection unit 7, but a stroke sensor attached to the steering hydraulic cylinders 2 and 3 may be used in addition to the potentiometer.

The present invention has an effect of improving operability regardless of the shape of the vehicle body, and is useful as a steering operation device.

Claims (1)

A hydraulic actuator driven by hydraulic pressure to change the steering angle of the vehicle;
A steering valve that adjusts the flow rate of oil supplied to the hydraulic actuator in accordance with the input pilot pressure;
A pilot pressure input to the steering valve is adjusted according to a difference between a displacement amount of the operation input member and a displacement amount of the feedback input member. A pilot valve,
A joystick lever which is provided so as to be tiltable by being operated by an operator, is connected to the operation input member, and displaces the operation input member according to a tilt angle;
A driving device for displacing the feedback input member in response to an input command signal;
A steering angle detector that detects the steering angle and outputs it as a detection signal;
A control unit that receives the detection signal from the steering angle detection unit and sends the command signal to the drive device so as to displace the feedback input member according to the steering angle;
A steering operation device comprising:

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